1. Field of the Invention
The present invention generally relates to frequency division duplex (FDD) mobile communications and particularly relates to achieving reduced interference between multiple FDD systems which allocate different frequencies.
2. Description of the Related Art
In general, as schemes for realizing full-duplex communications, there are an FDD scheme and a time division duplex (TDD) scheme. The FDD scheme uses different frequencies for transmission and reception to realize simultaneous transmission and reception. The TDD scheme alternately switches between transmit and receive timings to effectively realize simultaneous communications. Furthermore, the FDD and TDD schemes may be used together, and a frequency bandwidth allocated for FDD operations may be switched for use in the TDD scheme to adjust a balance of resources used in uplink and downlink and improve frequency utilization efficiency (see Patent document 1, for example). Moreover, there is also a method of varying duplex schemes to be used between neighboring cells, and improving on service areas and performance (see Patent document 2, for example.)
Patent document 1: Japanese translation (No, 2006-518562) of PCT application publication
Patent Document 2 JP2006-191649A